Add alerts about unreleased changes to gems

Alert GOV.UK teams about unreleased changes to the gems they own.

This should make us able to retire the https://github.com/alphagov/gem-release-alert repo

.github/workflows/gem_version_checker.yml

@@ -0,0 +1,28 @@
+name: "Gem Version Checker"
+
+on:
+  workflow_dispatch: {}
+  schedule:
+    - cron:  '00 13 * * 3' # Runs at 13:00 UTC, Every Wednesday.
+
+env:
+  SEAL_ORGANISATION: alphagov
+  GITHUB_TOKEN: ${{ secrets.GH_TOKEN }}
+  SLACK_WEBHOOK: ${{ secrets.SLACK_WEBHOOK }}
+
+jobs:
+  gem-version-checker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+
+      - name: Gem Version Checker
+        id: gem_version_checker
+        run: |
+          ./bin/seal_runner.rb gems

lib/gem_version_checker.rb

@@ -0,0 +1,36 @@
+require "uri"
+require "net/http"
+require "json"
+
+class GemVersionChecker
+  def detect_version_discrepancies(gem_name)
+    rubygems_version = fetch_rubygems_version(gem_name)
+    rubygems_version if rubygems_version && change_is_significant?(gem_name, rubygems_version)
+  end
+
+  def fetch_rubygems_version(gem_name)
+    uri = URI("https://rubygems.org/api/v1/gems/#{gem_name}.json")
+    res = Net::HTTP.get_response(uri)
+
+    JSON.parse(res.body)["version"] if res.is_a?(Net::HTTPSuccess)
+  end
+
+  def files_changed_since_tag(repo, tag)
+    Dir.mktmpdir do |path|
+      Dir.chdir(path) do
+        if system("git clone --recursive --depth 1 --shallow-submodules --no-single-branch https://github.com/alphagov/#{repo}.git > /dev/null 2>&1")
+          Dir.chdir(repo) { `git diff --name-only #{tag}`.split("\n") }
+        else
+          puts "Warning: Failed to clone #{repo}"
+          []
+        end
+      end
+    end
+  end
+
+  def change_is_significant?(repo_name, previous_version)
+    files_changed_since_tag(repo_name, "v#{previous_version}").any? do |path|
+      path.start_with?("app/", "lib/") || path == "CHANGELOG.md"
+    end
+  end
+end

lib/message_builder.rb

@@ -1,4 +1,5 @@
 require "pathname"
+require_relative "gem_version_checker"
 require_relative "github_fetcher"
 require_relative "message"
 
@@ -18,6 +19,8 @@ def build
       build_dependapanda_message
     when :ci
       build_ci_message
+    when :gems
+      build_gems_message
     else
       build_regular_message
     end
@@ -57,6 +60,33 @@ def build_ci_message
     Message.new(ci_message, mood: "robot_face")
   end
 
+  def build_gems_message
+    Message.new(gems_message, mood: "gem")
+  end
+
+  def gems_message
+    @alerts = all_govuk_gems.select { |gem| gem["team"] == team.channel }.map { |gem|
+      alert = GemVersionChecker.new.detect_version_discrepancies(gem["app_name"])
+      "<#{gem['links']['repo_url']}|#{gem['app_name']}> has unreleased changes since v#{alert}" if alert
+    }.compact
+
+    template_file = Pathname.new("#{TEMPLATE_DIR}/gem_alerts.text.erb")
+    ERB.new(template_file.read, trim_mode: "-").result(binding).strip
+  end
+
+  def all_govuk_gems
+    @all_govuk_gems ||= fetch_gems
+  end
+
+  def fetch_gems
+    res = Net::HTTP.get_response(URI("https://docs.publishing.service.gov.uk/gems.json"))
+
+    JSON.parse(res.body)
+  rescue StandardError => e
+    puts "Error fetching gems: #{e.message}"
+    []
+  end
+
   def ci_message
     @repos = check_team_repos_ci.reject { |_, v| v }.keys
     return nil if @repos.empty?

lib/seal.rb

@@ -38,6 +38,8 @@ def bark_at(team, mode: nil)
                 MessageBuilder.new(team, :ci).build if team.ci_checks
               when "seal_prs"
                 MessageBuilder.new(team, :seal).build if team.seal_prs
+              when "gems"
+                MessageBuilder.new(team, :gems).build if team.gems
               end
 
     return if message.nil? || message.text.nil?

lib/slack_poster.rb

@@ -60,6 +60,8 @@ def assign_poster_settings
         [":#{@season_symbol}angrier_seal:", "#{@season_name}Angry Seal"]
       when "robot_face"
         [":robot_face:", "Angry CI Robot"]
+      when "gem"
+        [":gem:", "Gem Release Robot"]
       when "tea"
         [":manatea:", "Tea Seal"]
       when "charter"

lib/team.rb

@@ -7,6 +7,7 @@ def initialize(
     afternoon_seal_quotes: nil,
     dependapanda: nil,
     ci_checks: nil,
+    gems: nil,
     compact: nil,
     exclude_labels: nil,
     exclude_titles: nil,
@@ -22,6 +23,7 @@ def initialize(
     @afternoon_seal_quotes = (afternoon_seal_quotes.nil? ? false : afternoon_seal_quotes)
     @dependapanda = (dependapanda.nil? ? false : dependapanda)
     @ci_checks = (ci_checks.nil? ? false : ci_checks)
+    @gems = (gems.nil? ? false : gems)
     @compact = (compact.nil? ? false : compact)
     @quotes_days = quotes_days || []
     @exclude_labels = exclude_labels || []
@@ -40,6 +42,7 @@ def initialize(
     afternoon_seal_quotes
     dependapanda
     ci_checks
+    gems
     compact
     exclude_labels
     exclude_titles

lib/team_builder.rb

@@ -46,6 +46,7 @@ def build_all_teams
         raise "#{team_name} is a GOV.UK team and shouldn't list repos in ./config/alphagov.yml"
       end
       team_config["ci_checks"] = is_govuk_team?(team_name)
+      team_config["gems"] = is_govuk_team?(team_name)
       Team.new(**apply_env(team_config))
     end
   end
@@ -60,6 +61,7 @@ def apply_env(config)
       afternoon_seal_quotes: env["AFTERNOON_SEAL_QUOTES"] == "true" || config["afternoon_seal_quotes"],
       dependapanda: env["DEPENDAPANDA"] == "true" || config["dependapanda"],
       ci_checks: env["CI_CHECKS"] == "true" || config["ci_checks"],
+      gems: env["GEMS"] == "true" || config["gems"],
       compact: env["COMPACT"] == "true" || config["compact"],
       exclude_labels: env["GITHUB_EXCLUDE_LABELS"]&.split(",") || config["exclude_labels"],
       exclude_titles: env["GITHUB_EXCLUDE_TITLES"]&.split(",") || config["exclude_titles"],

spec/gem_version_checker_spec.rb

@@ -0,0 +1,36 @@
+require "./lib/gem_version_checker"
+
+RSpec.describe GemVersionChecker do
+  subject(:gem_version_checker) { described_class.new }
+
+  let(:slack_poster) { instance_double(SlackPoster, send_request: nil) }
+
+  before do
+    allow(SlackPoster).to receive(:new).and_return(slack_poster)
+  end
+
+  it "fetches version number of a gem from rubygems" do
+    stub_rubygems_call("6.0.1")
+
+    expect(gem_version_checker.fetch_rubygems_version("example")).to eq("6.0.1")
+  end
+
+  it "detects when there are files changed since the last release that are built into the gem" do
+    stub_rubygems_call("1.2.2")
+    stub_files_changed_since_tag(["lib/foo.rb"])
+
+    expect(gem_version_checker.detect_version_discrepancies("example")).to match("1.2.2")
+  end
+
+  def stub_files_changed_since_tag(files)
+    allow(gem_version_checker).to receive(:files_changed_since_tag) do
+      files
+    end
+  end
+
+  def stub_rubygems_call(version)
+    repo = { "version": version }
+    stub_request(:get, "https://rubygems.org/api/v1/gems/example.json")
+      .to_return(status: 200, body: repo.to_json, headers: {})
+  end
+end

templates/gem_alerts.text.erb

@@ -0,0 +1,3 @@
+<% @alerts.each do |alert| -%>
+<%= alert %>
+<% end -%>